Title:
TOUGHNESS ENHANCED SILICON-CONTAINING COMPOSITE BODIES, AND METHODS FOR MAKING SAME
Document Type and Number:
WIPO Patent Application WO2003084872
Kind Code:
A3
Abstract:
A silicon-containing composite body that would otherwise be brittle can be engineered to exhibit enhanced fracture toughness. Specifically, a silicon ceramic reinforced silicon carbide composite body is produced, preferably by a reactive infiltration technique. The ceramic is selected such that it has a higher coefficient of thermal expansion (CTE) than does the silicon phase. At least at some point during processing, the silicon phase is at temperature above its normal ductile/brittle transition temperature of about 500°C, and preferably above its melting point. The formed composite body containing the silicon phase is then cooled below its ductile/brittle transition. During cooking the ceramic phase shrinks more than does the silicon phase, thereby placing the latter in a state of compressive stress. By the time the composite body has cooled to substantially ambient temperature, the induced compressive stress in the silicon phase is sufficient as to impart a measurable degree of semi-ductile character to the silicon phase. This pseudo-ductility manifests itself in the composite body as a significant increase in the fracture toughness of the body. For example when the ceramic reinforcement of the carbide (which has a CTE similar to that of silicon), fracture toughness increased by almost 30 percent.
Inventors:
AGHAJANIAN MICHAEL K (US)
Application Number:
PCT/US2002/032823
Publication Date:
March 18, 2004
Filing Date:
October 15, 2002
Export Citation:
Assignee:
M CUBED TECHNOLOGIES INC (US)
AGHAJANIAN MICHAEL K (US)
AGHAJANIAN MICHAEL K (US)
International Classes:
C04B35/563; C04B35/573; F41H5/04; (IPC1-7): C04B35/573; C04B35/563; C04B35/577; F41H5/04
Domestic Patent References:
| WO2000062007A2 | 2000-10-19 |
Foreign References:
| EP0798281A2 | 1997-10-01 | |||
| US5962103A | 1999-10-05 | |||
| US3859399A | 1975-01-07 |
Other References:
IN SUB HAN ET AL: "IMPROVEMENT OF MECHANICAL PROPERTIES IN RBSC BY BORON CARBIDE ADDITION", JOURNAL OF MATERIALS SCIENCE LETTERS, CHAPMAN AND HALL LTD. LONDON, GB, vol. 21, no. 9, 1 May 2002 (2002-05-01), pages 703 - 706, XP001125550, ISSN: 0261-8028
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